diff --git a/docs/en/product_documents/tools/tool_usb_downloader.md b/docs/en/product_documents/tools/tool_usb_downloader.md
index 4be27415..d032a027 100644
--- a/docs/en/product_documents/tools/tool_usb_downloader.md
+++ b/docs/en/product_documents/tools/tool_usb_downloader.md
@@ -27,8 +27,8 @@ There are two reserved pins(RTS, DTR) on M5Stack USB Downloader for other applic
 ## DOCUMENTS
 
 - [Schematic](https://github.com/watson8544/M5Stack-UserGuide/blob/master/TOOLS_DOCS/USBtool.pdf)
-- [UserGuide](https://github.com/watson8544/M5Stack-UserGuide/blob/master/TOOLS_DOCS/M5Stack-USB-Downloader-UserGuide)
+- [UserGuide](https://github.com/watson8544/M5Stack-UserGuide/blob/master/TOOLS_DOCS/M5Stack-USB-Downloader-UserGuide.md)
 
 <!-- <figure>
     <img src="assets/img/product_pics/units/M5GO_Unit_moisture.jpg" height="50" width="49">
-</figure> -->
\ No newline at end of file
+</figure> -->
diff --git a/docs/ja/product_documents/tools/tool_usb_downloader.md b/docs/ja/product_documents/tools/tool_usb_downloader.md
index 5c58647d..f6a7a75d 100644
--- a/docs/ja/product_documents/tools/tool_usb_downloader.md
+++ b/docs/ja/product_documents/tools/tool_usb_downloader.md
@@ -27,7 +27,7 @@
 - 回路図
   - [Schematic](https://github.com/watson8544/M5Stack-UserGuide/blob/master/TOOLS_DOCS/USBtool.pdf)
 - ユーザガイド(英語)
-  - [UserGuide](https://github.com/watson8544/M5Stack-UserGuide/blob/master/TOOLS_DOCS/M5Stack-USB-Downloader-UserGuide)
+  - [UserGuide](https://github.com/watson8544/M5Stack-UserGuide/blob/master/TOOLS_DOCS/M5Stack-USB-Downloader-UserGuide.md)
 
 <!-- <figure>
     <img src="assets/img/product_pics/units/M5GO_Unit_moisture.jpg" height="50" width="49">
diff --git a/docs/zh_CN/product_documents/tools/tool_usb_downloader.md b/docs/zh_CN/product_documents/tools/tool_usb_downloader.md
index 4be27415..d032a027 100644
--- a/docs/zh_CN/product_documents/tools/tool_usb_downloader.md
+++ b/docs/zh_CN/product_documents/tools/tool_usb_downloader.md
@@ -27,8 +27,8 @@ There are two reserved pins(RTS, DTR) on M5Stack USB Downloader for other applic
 ## DOCUMENTS
 
 - [Schematic](https://github.com/watson8544/M5Stack-UserGuide/blob/master/TOOLS_DOCS/USBtool.pdf)
-- [UserGuide](https://github.com/watson8544/M5Stack-UserGuide/blob/master/TOOLS_DOCS/M5Stack-USB-Downloader-UserGuide)
+- [UserGuide](https://github.com/watson8544/M5Stack-UserGuide/blob/master/TOOLS_DOCS/M5Stack-USB-Downloader-UserGuide.md)
 
 <!-- <figure>
     <img src="assets/img/product_pics/units/M5GO_Unit_moisture.jpg" height="50" width="49">
-</figure> -->
\ No newline at end of file
+</figure> -->